Haiku: Process/thread management functions

[trungnt2910]

Add support for process/thread management functions in System.Diagnostics.Process for Haiku.

This is required to build managed runtime libraries for Haiku as well as running a simple "Hello, World!" application.

Part of #55803.

[trungnt2910]

C/c @am11

I just added the relevant parts of the common files to both, then we can rebase stuff later.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-diagnostics-process
See info in area-owners.md if you want to be subscribed.

[Copilot]

Pull request overview

This PR adds Haiku operating system support to the System.Diagnostics.Process library, enabling process and thread management functionality for Haiku. This is part of the broader effort to support Haiku as a platform (#55803).

• Implements Haiku-specific process/thread management APIs using native Haiku system calls
• Adds proper platform attribute annotations for API surface compatibility
• Integrates Haiku interop layer for process, thread, and image information

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
ProcessThread.cs	Adds [SupportedOSPlatform("haiku")] attributes to PriorityLevel property getter and setter
ProcessThread.Haiku.cs	Implements Haiku-specific thread priority management and processor time tracking using native BeOS-style priority values
ProcessManager.Haiku.cs	Implements process enumeration, module collection, and process information retrieval for Haiku using team and thread APIs
Process.cs	Adds [UnsupportedOSPlatform("haiku")] attributes to working set limit properties
Process.Haiku.cs	Implements Haiku-specific process properties including boot time caching, start time, processor time tracking, and platform-specific helper methods
System.Diagnostics.Process.csproj	Adds Haiku target framework and includes Haiku-specific source files and interop definitions
Interop.OS.cs	Defines Haiku native interop for OS-level APIs including team/thread/area/system information structures and P/Invoke declarations
Interop.Libraries.cs	Defines the libroot library constant for Haiku native library imports
Interop.Image.cs	Defines Haiku native interop for image (module) information APIs

[Copilot]

The setter is missing [SupportedOSPlatform("linux")] and [SupportedOSPlatform("freebsd")] attributes. While these platforms throw PlatformNotSupportedException in their implementations, the attributes on the public API should match the getter's attributes to maintain consistency and accuracy in the API surface declarations. The presence of the getter attribute for these platforms indicates the API should be callable, even if it throws at runtime.

Suggested change

	[SupportedOSPlatform("windows")]
	[SupportedOSPlatform("windows")]
	[SupportedOSPlatform("linux")]
	[SupportedOSPlatform("freebsd")]

[trungnt2910]

Ignoring since it's not related to Haiku.

[huoyaoyuan]

Nit: if it's not interested to invoke them from managed code, you can define them as opaque IntPtr.

[trungnt2910]

Maybe an opaque void* instead, since the other members are void*?

Those two correspond to https://github.com/haiku/haiku/blob/d39ce117e02d3d8aac966b1a46bd955a2b59c069/headers/os/kernel/image.h#L27-L28 in the Haiku source.

	void		(*init_routine)();
	void		(*term_routine)();

[huoyaoyuan]

Semantic-wise void* is incorrect because function pointers can't be dereferenced. In C function pointers can't be casted to void* either. IntPtr is correct for opaque pointer-size field. Unmanaged function pointer is precise but unnecessary.